Boss PS-3 specs (exp ring/tip max voltage)

hello- in conceptualizing a custom project involving expression pedal control- ive been collecting data on the various pedals involved- mainly the max voltage allowable on the tip/ring. thus far- all companies ive contacted have been quite helpful in providing the specs on their products (ehx- empress- guyatone- robot factory). however- in contacting roland/boss regarding the PS-3 i got the following response:

"Unfortunately, the input spec for the EXP jack on the PS-3 is not published by BOSS Japan.
We can only recommend that you use the EV-5 or FV-500H/L with the PS-3."

1. im not sure what boss japan has to do with anything. 2. why wouldnt boss provide this information? 3. does anyone happen to know the ring/tip max voltage for the expression input on a PS-3?

thanks in advance for any help you can provide- as the response i got was both extremely unhelpful and surprising.

1. Because they design and build the thing, and so it follows that they produce and publish the specifications.

2. I don't think they are deliberately concealing the information. What they (I'm assuming you contacted Boss USA?) are saying is that they don't have the information provided to them, so they can't provide it to you.